ML20116E581
| ML20116E581 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 05/11/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20116D885 | List:
|
| References | |
| FOIA-96-237 NUDOCS 9608060046 | |
| Download: ML20116E581 (5) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D. C. 20555
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ENCLOSURE 1 l
SAFETY EVA! UATION REPORT REQUEST FOR XRDIDRDlTTO TECHNICAL SPECIFICATIONS FOR CALVtRT CLIFP5 NUCLEAR POWER PLANT, UNIT 5 1 & 2 l
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1.0 INTRODUCTION
In correspondence dated June 16,1988(Ref1),BaltimoreGasandElectric Company (BG&E) requested amendments to the Technical Specifications (TS) for l-the Calvert Cliffs Nuclear Power Plant, Units I and 2 (CC-1/2).
The proposed amendments address operability and calibration requirements for the core exit thermocouples(CETs).
The CETs are identified in Regulatory Guide 1.97 as Category 1 instrumentation for indi ating the potential for fuel cladding failure. The instrumentation l
used for indicating the status of Category 1 variables should be qualified in accordance with 10 CFR 50.49.
In the submittal (Ref 1), the licensee proposes the use of unqualified CETs l
during the interim period before all CETs are upgraded with qualified connec-tors. Additionally, BG&E added CET surveillance requirements to CC-1/2 TS Table 4.3-10.
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In a letter to BG&E dated August 21, 1989 (Ref 2), the staff requested the following additional information:
1)
Location of qualified and unqualified CETs 2)
Bases for not periodically calibrating the thermocouple portion of the CET instrument strings 3)
Identification of the electronic components and the location of the test signal input in the instrument string 4)
Certification that no degradation or failures in the CET system could occur that would be undetected 5)
A schedule for replacement of the unqualified thermocouples 6)
Technical justification for the difference between licensee's Limiting Condition of Operation (LCO) and the CE Owners Group (CEOG) Restructured Standard Technical Specifications (RSTS) LCO.
This Safety Evaluation Report discusses the licensee's proposed modifications ano responses to the above items.
2.0 EVALUATION The licensee originally requested a TS change to allow substitution of unquali-fied CET channels for a qualified, but inoperable, CET channel until all CETs could be upgraded. However, in response to a RAI (Ref 2), the licensee states j
that there are now at least five qualified CETs per core quadrant in each unit (Ref3). Since a minimum of two independent sets of two qualified CETs per core quadrant are required to be operable, the licensee has removed the proposed footnote from Table 3.3-10.
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While there are now at least five CETs per core quadrant, the licensee must also ensure that there are two independent, safety grade channels of CETs per core quadrant. The CET channel includes the safety grade power supply for all the CETs in that channel. Loss of a power supply will result in loss of all CETs powered by that supply. Consequently, even though there are five quali-tied CETs per core quadrant, a unit could still be in a LC0 if all five C[Ts are powered off the same safety grade power supply.
Additionally, the distribution of CETs in a channel must be such that the quadrant radial enthalpy (temperature) gradient may be monitored. That is, the remaining operable CETs in a channel must be distributeo such that there is at least one CET near the center of the core, and one CET near the core perimeter, in each quadrant.
The licensee's map of CET locations (Ref 3) does not provide sufficient cetail to confirm this channel distribution of qualified CETs.
The licensee requests addition of the CETs to Table 3.3-10.
The licensee's time limit for returning a CET Channel to OPERABLE status is specified by Action Statement 31. This Action Statement requires, "With the number of OPERABLE post-accident monitoring channels [one] less than required by Table 3.3-10, either restore the inoperable channel to OPERABLE status within 30 days or be in HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />."
The licensee identified the electronic components that are to be included in the CET channel calibrations. With the exception of the Channel power supplies, all electronic components in the instrument channel are included in the channel calibrations. The licensee states that it is not feasible to i
recalibrate the sensor portion of a CET after the CET is installed in the cure.
The licensee references a Combustion Engineering Owners Group (CE0G) report that indicates the majority of operational CETs are ncrmally within 10F* of l
one another, and instrument crift is negligible. The staff concurs that it may not be feasible to remove a CET sensor soley to recalibrate the sensor.
Nevertheless, the licensee must demonstrate, through periodic surveillance, that the CETs respond as designed. This can be accomplished in part by performing a cross-comparison of the output of different sensors that have a known relationship to each other. Another acceptable method for verifying stability of the CET sensors is to compare the output of different sensors under isothermal conditions (all sensors at the same temperature) over a range of temperatures, in lieu of calibrating the CETs using an accepted calibration standard. The licensee states that the CETs are compared to hot leg RTDs, which, according to TS Table-4.3-10, are calibrated each refueling outage. A l
CET will be considered IN0PERABLE if the temperature difference between RTD and CET is greater than 45F'.
This method of verifying operability within design parameters is acceptable.
The licensee states that the schedule for replacing a CET is dependent on the depletion of four rhodium neutron detectors in the associated Incore Instrument string. Consequently, the number of channels to be replaced each refueling outage can be only estimated. The licensee's predicted schedule of CET replacement indicates the unqualified CETs will be replaced over the next two refueling outages. Given the number of qualified CETs now installed in each unit, this schedule appears reasonable.
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l The licensee requests staff approval to add the CETs to TS Table 4.3-10
" Post-Accident Monitoring Instrumentation Surveillance Requirements." The CET channel check and channel calibration are to be performed at the same frequency as other instrumentation in this table. The provisions of this amendment of 1
the surveillance and calibration frequency requirements are consistent with the surveillance and calibratiun requirements for other methods of detecting the l
onset of inadequate core cooling (reactor vessel level and subcooling indica-i tions). This amendment is acceptable.
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3.0 CONCLUSION
The licensee has at least five Qualified CETs per core quadrant in each unit, and has committed to replacing all unqualified CETs with qualified instrumen-tatiun over the next two refueling outages. Provided the qualified CETs are in two independently powered channels, and are located in the core such that radial temperature distributions may be determined for each core quadrant, this commitment will insure there is adequate instrumentation (approximately 45 l
CETs) available to determine ICC by monitoring core exit coolant temperatures.
l The licensee's requested inclusion of the CET instrumentation operability i
requirement (30 days to restore the required minimum operable channels) is acceptable. The 30-day instrumentation surveillance interval is acceptable.
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4 References 1)
Letter from J. A. Tiernan (BG&E) to NRC Document Control Desk, dated June 16, 1988, "Calvert Cliffs Nuclear Power Plant Unit Nos. 1 & 2; Docket Nos. 50-317 & 50-318, Request for Amendment."
2)
Letter from S. A. McNeil (NRC) to G. C. Creel (BG&E), dated August 21, 1989, " Request for Additional Information - Technical Specifications for the Core Exit Thermocouple System (Unit 1 TAC 69244; Unit 2 TAC 69245)."
3)
Letter from G. C. Creel (BG&E) to NRC Document Control Desk, dated September 20, 1989, " Response to Request for Additional Information Regarding Core Exit Thermocouples."
4)
NRC Generic Letter 83-37, "NUREG-0737 Technical Specifications," dated November 1, 1983.
5)
" Standard Technical Specifications for Combustion Engineering Pressurized Water Reactors," NUREG-0212, Draft Revision 3, July 9,1982.
6)
" Combustion Engineering Owners Group (CE0G) Restructured Technical Specification (RSTS)," CEN-355, May 26, 1989.
l ENCLOSURE 2 SALP INPUT FACILITY NAME:
Calvert Cliffs Nuclear Power Plant, Units No.1 & 2
SUMMARY
OF REVIEW:
The instrumentation aspects of the Technical Specification changes proposed by the licensee for the Calvert Cliffs Nuclear Power Plant Units No. 1 & 2 were reviewed by SICB/ DST /NRR staff. The proposed changes to the surveillance interval, and the replacement of the unqualified Core Exit Thermocouples (CETs) with safety-rated CETs enhances the safe operation of the units. The proposed use of the existing ACTION STATEMENTS for restoration of an inoperable channel to OPERABLE status is consistent with staff recommendations.
NARRATIVE DISCUSSION OF LICENSEE PERFORMANCE FUNCTIONAL AREA-ENGINEERING / TECHNICAL SUPPORT:
The licensee's commitment to replace nonsafety-rated CETs with safety-rated CETS indicates the licensee is willing to improve the safe operation of their Units. The timely and comprehensive submittals indicate adequate staffing.
AUTHOR: Michael E. Waterman DATE:
02/12/90 1
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Robert A. Capra Table 3.3-10, the inoperable channel must be restored to operability within 30 days or the unit must be in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The licensee's request is acceptable.
An evaluation of licensee performance (SALP input) is provided as Enclosure 2.
Original signed byt
Scott Newberry, Chf f Instrumentation an! Control Systems Branch Division of Systems Technology
Enclosures:
As stated DISTRIBUTION, Central File cc w/ enclosures:
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